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fix bug in ackerman reduction found by Anvesh

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2013-09-24 10:42:31 +03:00
parent 2d01c4d50f
commit 1b8d1a1ccc
2 changed files with 79 additions and 40 deletions
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116
src/muz/transforms/dl_mk_array_blast.cpp
View file

@ -31,7 +31,6 @@ namespace datalog {
rm(ctx.get_rule_manager()),
m_rewriter(m, m_params),
m_simplifier(ctx),
m_sub(m),
m_next_var(0) {
m_params.set_bool("expand_select_store",true);
m_rewriter.updt_params(m_params);
@ -82,7 +81,6 @@ namespace datalog {
return false;
}
if (v) {
m_sub.insert(e, v);
m_defs.insert(e, to_var(v));
}
else {
@ -92,71 +90,113 @@ namespace datalog {
m_next_var = vars.size() + 1;
}
v = m.mk_var(m_next_var, m.get_sort(e));
m_sub.insert(e, v);
m_defs.insert(e, v);
++m_next_var;
}
return true;
}
bool mk_array_blast::is_select_eq_var(expr* e, app*& s, var*& v) const {
expr* x, *y;
if (m.is_eq(e, x, y) || m.is_iff(e, x, y)) {
if (a.is_select(y)) {
std::swap(x,y);
}
if (a.is_select(x) && is_var(y)) {
s = to_app(x);
v = to_var(y);
return true;
}
}
return false;
}
bool mk_array_blast::ackermanize(rule const& r, expr_ref& body, expr_ref& head) {
expr_ref_vector conjs(m);
expr_ref_vector conjs(m), trail(m);
qe::flatten_and(body, conjs);
m_defs.reset();
m_sub.reset();
m_next_var = 0;
ptr_vector<expr> todo;
todo.push_back(head);
obj_map<expr, expr*> cache;
ptr_vector<expr> args;
app_ref e1(m);
app* s;
var* v;
for (unsigned i = 0; i < conjs.size(); ++i) {
expr* e = conjs[i].get();
expr* x, *y;
if (m.is_eq(e, x, y) || m.is_iff(e, x, y)) {
if (a.is_select(y)) {
std::swap(x,y);
}
if (a.is_select(x) && is_var(y)) {
if (!insert_def(r, to_app(x), to_var(y))) {
return false;
}
}
if (is_select_eq_var(e, s, v)) {
todo.append(s->get_num_args(), s->get_args());
}
if (a.is_select(e) && !insert_def(r, to_app(e), 0)) {
return false;
else {
todo.push_back(e);
}
todo.push_back(e);
}
// now make sure to cover all occurrences.
ast_mark mark;
while (!todo.empty()) {
expr* e = todo.back();
todo.pop_back();
if (mark.is_marked(e)) {
if (cache.contains(e)) {
todo.pop_back();
continue;
}
mark.mark(e, true);
if (is_var(e)) {
cache.insert(e, e);
todo.pop_back();
continue;
}
if (!is_app(e)) {
return false;
}
app* ap = to_app(e);
if (a.is_select(ap) && !m_defs.contains(ap)) {
if (!insert_def(r, ap, 0)) {
return false;
bool valid = true;
args.reset();
for (unsigned i = 0; i < ap->get_num_args(); ++i) {
expr* arg;
if (cache.find(ap->get_arg(i), arg)) {
args.push_back(arg);
}
else {
todo.push_back(ap->get_arg(i));
valid = false;
}
}
if (a.is_select(e)) {
get_select_args(e, todo);
continue;
if (valid) {
todo.pop_back();
e1 = m.mk_app(ap->get_decl(), args.size(), args.c_ptr());
trail.push_back(e1);
if (a.is_select(ap)) {
if (m_defs.find(e1, v)) {
cache.insert(e, v);
}
else if (!insert_def(r, e1, 0)) {
return false;
}
else {
cache.insert(e, m_defs.find(e1));
}
}
else {
cache.insert(e, e1);
}
}
}
for (unsigned i = 0; i < conjs.size(); ++i) {
expr* e = conjs[i].get();
if (is_select_eq_var(e, s, v)) {
args.reset();
for (unsigned j = 0; j < s->get_num_args(); ++j) {
args.push_back(cache.find(s->get_arg(j)));
}
e1 = m.mk_app(s->get_decl(), args.size(), args.c_ptr());
if (!m_defs.contains(e1) && !insert_def(r, e1, v)) {
return false;
}
conjs[i] = m.mk_eq(v, m_defs.find(e1));
}
for (unsigned i = 0; i < ap->get_num_args(); ++i) {
todo.push_back(ap->get_arg(i));
else {
conjs[i] = cache.find(e);
}
}
m_sub(body);
m_sub(head);
conjs.reset();
// perform the Ackermann reduction by creating implications
// i1 = i2 => val1 = val2 for each equality pair:
@ -171,6 +211,7 @@ namespace datalog {
for (; it2 != end; ++it2) {
app* a2 = it2->m_key;
var* v2 = it2->m_value;
TRACE("dl", tout << mk_pp(a1, m) << " " << mk_pp(a2, m) << "\n";);
if (get_select(a1) != get_select(a2)) {
continue;
}
@ -184,10 +225,7 @@ namespace datalog {
conjs.push_back(m.mk_implies(m.mk_and(eqs.size(), eqs.c_ptr()), m.mk_eq(v1, v2)));
}
}
if (!conjs.empty()) {
conjs.push_back(body);
body = m.mk_and(conjs.size(), conjs.c_ptr());
}
body = m.mk_and(conjs.size(), conjs.c_ptr());
m_rewriter(body);
return true;
}

3
src/muz/transforms/dl_mk_array_blast.h
View file

@ -44,7 +44,6 @@ namespace datalog {
mk_interp_tail_simplifier m_simplifier;
defs_t m_defs;
expr_safe_replace m_sub;
unsigned m_next_var;
bool blast(rule& r, rule_set& new_rules);
@ -59,6 +58,8 @@ namespace datalog {
bool insert_def(rule const& r, app* e, var* v);
bool is_select_eq_var(expr* e, app*& s, var*& v) const;
public:
/**
\brief Create rule transformer that removes array stores and selects by ackermannization.